Photochemical bleaching of olefin sulfonates

ABSTRACT

THE PROCESS FOR DECOLORIZING SULFONATED A-OLEFIN REACTION PRODUCTS WHICH COMPRISIES IRRADIATING A SOLUTION OF SULFONATED A-OLEFIN OR HYDROLYSATE THEREOF WITH ELECTROMAGNETIC RADIATION IN THE RANGE OF ABOUT 2,000 TO ABOUT 7,000 ANGSTROMS IN THE PRESENCE OF HYDROGEN PEROXIDE AND A SOLVENT HAVING LOW ABSORPTIVITY FOR IRRADIATION. THE DECOLORIZED SULFONATED A-OLEFIN REACTION PRODUCTS ARE EXCELLENT DETERGENT COMPOUNDS AND ARE ADAPTED TO APPLICTION IN DETERGENT FORMULATIONS WHICH ARE SUBSTANTIALLY WHITE IN APPEARANCE.

United States Patent 3,585,116 PHOTOCHEMICAL BLEACHING OF OLEFIN SULFONATES Ted J. Logan, Colerain Township, Hamilton County, and Paul J. Kropp, Springfield Township, Hamilton County, Ohio, assignors to The Procter & Gamble Company, Cincinnati, Ohio No Drawing. Filed Nov. 4, 1968, Ser. No. 773,353 Int. Cl. B01j 1/10 U.S. Cl. 204-158R 9 Claims ABSTRACT OF THE DISCLOSURE The process for decolorizing sulfonated u-olefin reaction products which comprises irradiating a solution of sulfonated wolefin or hydrolysate thereof with electromagnetic radiation in the range of about 2,000 to about 7,000 angstroms in the presence of hydrogen peroxide and a solvent having low absorptivity for irradiation. The decolorized sulfonated a-olefin reaction products are excellent detergent compounds and are adapted to application in detergent formulations which are substantially white in appearance.

FIELD OF THE INVENTION This invention relates to a process of bleaching olefin sulfonate detergent compounds. More particularly, it relates to a photochemical method of improving the appearance of olefin sulfonates thereby resulting in the preparation of products which are more attractive and adapted to use in detergent compositions.

Olefin sulfonate detergent compounds are known materials and are described, for example, in U.S. Pats. 2,061,- 618 (Nov. 24, 1936); 2,865,958 (Dec. 23, 1958); 2,940,- 936 (June 14, 1960); and 3,332,874 through 3,332,880 (July 25, 1967) and in German Pat. 1,185,178 (Jan. 14, 1965) and Canadian Pat. 775,142 (Jan. 2, 1968). These materials have excellent detergency properties and are generally prepared by sulfonation of an olefin, such as an alpha olefin, with a sulfonating agent, e.g. S0 followed by hydrolysis to produce sulfonic acids and/ or salts thereof. While the olefin sulfonates are especially suited to wide application by virtue of their excellent detergency properties, they tend to have undesirable color characteristics and vary in color from light yellow to blackish brown. These undesirable color characteristics detract from the overall attractiveness and acceptability of detergent formulations containing these materials and are unattractive from a commercial standpoint.

Attempts have been made in the art to decolorize olefin sulfonate detergent products. German Pat. 1,185,178 (Jan. 14, 1965) describes a process of bleaching raw acid sulfonation products and their acidic, neutral or alkaline hydrolysates at temperatures of 20 C. to 100 C. with hydrogen peroxide, alkali chlorites or alkali hypochlorites. While peroxidic bleaching of olefin sulfonates makes possible the preparation of materials of improved color characteristics, the bleaching is relatively inefiicient, often requiring extended periods of time.

Another method of decolorizing olefin sulfonates is described in Canadian Pat. 775,142 (Jan. 2, 1968) whereby an olefin sulfonate is improved in color by subjecting the olefin sulfonate in a dry state, preferably in powdered form, to ultraviolet radiation. In addition to requiring extended irradiation, the disclosed process requires the step of drying the olefin sulfonate to remove water prior to the irradiation with ultraviolet light.

It is an object of this invention to provide olefin sulfonates of outstanding detergent properties and improved color characteristics.

It is another object of the present invention to provide an efiicient process for improving the color of olefin sulfonate reaction products.

It is still another object of the present invention to provide an efficient process for photobleaching olefin sulfonate reaction products in the presence of a solvent or other vehicle.

Other objects of the present invention will become apparent from consideration of the detailed description of the invention which appears hereinafter.

SUMMARY OF THE INVENTION These and other objects of the present invention are achieved according to the present invention by the provision of a process for the bleaching of sulfonated a-olefin reaction products which comprises irradiating a solution of a sulfonated reaction product and a solvent having low absorptivity for irradiation with electromagnetic ra diation in the range of about 2000 to about 7000 angstroms, the irradiation being conducted in the presence of hydrogen peroxide. In accordance with the present invention sulfonated a-olefin reaction products are photobleached by a process which comprises dissolving the sulfonated a-olefin reaction product in an appropriate solvent of low irradiative absorptivity and irradiating in the presence of hydrogen peroxide for a period sufficient to effect an improvement in the color characteristics of the sulfonated product. The photobleaching process of the present invention provides olefiin sulfonate detergent materials having excellent detergency properties. Moreover, their color characteristics are such that they are aesthetically adapted to use in detergent formulations which are light in color, e.g., substantially white in appearance.

DETAILED DESCRIPTION OF THE INVENTION The photochemical bleaching process of the present invention is conveniently practiced by irradiating with a suitable radiation source hereinafter described a solution of sulfonated a-olefin reaction product in a solvent of low irradiative absorptivity in the presence of hydrogen peroxide. Appropriate solvents herein are those which are substantially non-interfering. Non-interfering solvents as defined herein are those solvents which are capable of dissolving the sulfonated a-olefin reaction product and hydrogen peroxide employed herein and which do not by absorption interfere with the transmission of electromagnetic irradiation hereinafter described or react with the hydrogen peroxide. Suitable non-interfering solvents are characterized by low absorptivity for radiation in the ranges hereinafter specified. These solvents normally transmit at least about 10% of the incident light. Organic solvents which absorb substantial amounts of incident radiation and/or interfere with the photobleaching process by conversion to undesirable side products are to be avoided.

Suitable solvents are to be found in such materials as water, alkanols, alkyl ethers, aromatic ethers, mixed alkyl aromatic ethers, cyclic ethers and glycol ethers. Examples of suitable alcohol solvents include alkyl monohydric alcohols of from 1 to about 10 carbon atoms, as for example, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, t-butyl alcohol, 2-ethyl hexyl alcohol and n-decyl alcohol. Aliphatic dihydric alcohols include those having from 2 to about 10 carbon atoms, as for example alkylene glycols such as ethylene glycol, 1,3-propanediol, 1,6-dihydroxyhexane and 1,10-dihydroxydecane.

Examples of suitable ether solvents are those having from 2 to about 10 carbon atoms including dialkyl ethers such as dimethyl ether, diethyl ether, di-n-butyl ether, dioctyl ether, diaryl ethers such as diphenyl ether, mixed alkyl aryl ethers such as methyl phenyl ether, cy-

clic monooxy ethers such as tetrahydrofuran, cyclic dioxy ethers such as dioxane and glycol ethers such as 1,2-dimethoxyethane and diethylene glycol dirnethyl ether.

Preferred solvents are water and the alkanols for the reasons that they are readily available, do not interfere by reaction with the irradiation treatment, and have low absorptivity for radiation under the conditions employed herein. It will be appreciated that the foregoing exemplary solvents can be used in combination. Other solvents similarly non-interfering in nature may likewise be employed to advantage.

The solutions photobleached according to the present invention contain the sulfonated a-olefin reaction product in an amount by weight of from about 0.01% to about 50%. While solutions wherein the sulfonated product is present in amounts in excess of the limit of solubility can be employed, it is preferable from the standpoint of efficiency of operation and uniformity in decolorization to employ solutions having the dissolved material present in an amount approximating the limit of solubility, The limit of solubility of such materials depends normally upon the particular solvent employed and the form in which the sulfonated product exists. For example, the ammoniumand alkali metal-containing salt forms of sulfonated u-olefins are more soluble in water than the acid mix from which the neutralized forms are obtained. When the photochemical process of this invention is conducted in a water solvent, the sulfonated u-olefin reaction product is preferably present in an amount of about 30% to about 40%, based on the weight of the solution irradiated in the manner described herein.

The solutions photobleached herein are prepared by mixing the sulfonated a-olefin reaction product, non-interfering solvent of the hereinbefore described type and the hydrogen peroxide component in any order. While the hydrogen peroxide can be added in a 100% hydrogen peroxide form, it is normally employed in diluted form. For example, a 30% aqueous solution is employed and is added to a solution of the sulfonated u-olefin in an amount to provide the desired hydrogen peroxide concentration. The amount of hydrogen peroxide employed is about 0.3% to about by weight of the sulfonated a-olefin reaction product. A preferred range is from about 0.6% to about 6% by weight hydrogen peroxide. Amounts in excess of about 10% are to be avoided since they tend to result in excessive foaming of the sulfonated ot-olefin solution. Moreover, the use of large amounts of peroxide results in the preparation of products having high residual peroxide content requiring a subsequent sulfite treatment to neutralize excess peroxide. If there is a need for such treatment, sodium sulfite is ordinarily employed.

The source of hydrogen peroxide employed herein can be either hydrogen peroxide per se or any of the materials commonly employed in the bleaching arts which in aqueous solutions split out hydrogen peroxides, e.g., perborates, persulfates and the like. Examples of these are the alkali metal perborates, e.g., sodium perborate and the alkali metal persulfates, e.g., sodium persulfate, potassium persulfate.

The reaction vessels used in the irradiation of olefin sulfonate materials herein are not critical and include quartz, Vycor, Corex, Pyrex, or common soft glass reaction vessels. Pyrex reaction vessels are preferred for use in this photochemical reaction. The photochemical bleaching process of the present invention can be carried out in conventional photochemical reaction vessels. A convenient method of practicing the present invention comprises irradiating a solution hereinbefore described in a standard Pyrex reaction vessel equipped with means for a nitrogen purge to provide agitation of the solution during irradiation and having immersed therein a jacketed, water-cooled quartz, Vycor, or Pyrex immersion well into which is placed a radiating light source. When direct sunlight is employed as the radiation source, a convenient method of effecting the photochemical reaction of the present invention is to place a solution of the olefin sulfonate in a conventional reaction vessel into the path of directly incident sunlight.

The electromagnetic radiation which is employed in the photochemical bleaching process of the present invention is light having a wavelength of about 2000 to about 7000 angstroms and includes light in the ultraviolet and visible ranges. The radiation employed herein is preferably in the range of 2800 to 7000 angstroms and is preferred from the standpoint of efficient photobleaching results.

Any radiation source which emits photo energy in the 2000 to 7000 angstrom range can be employed. For example, suitable sources include black light mercury vapor lamps, photofiood lamps, sunlamps, sunlight and the like. Similarly, lamps which operate on the principle of a zinc, cadmium, thallium, gallium, indium, carbon, zirconium, hydrogen, deuterium, xenon, or helium arc can be likewise employed in the exercise of the present invention.

The light sources employed herein are those which have substantial intensity. Substantial intensity as employed herein refers to light of sufficient intensity to provide the irradiated sample with about l 10- to about 1 10 einsteins/sec./cm. Natural daylight, as opposed to directly incident sunlight, is not suitable inasmuch as its intensity is not substantial as employed herein and does not effect appreciable photobleaching.

Preferred lamps for employment in the present invention include commercially available high-pressure mercury arc lamps having a total power capacity ranging from about 50 watts to about 10,000 watts, preferably from about watts to about 600 watts. These lamps emit a broad spectrum of light including ultraviolet radiation. Also preferred are the low-pressure mercury lamps having a total power capacity ranging from about 0.5 watt to about 50 watts, preferably from about 0.5 watt to about 2 watts. These lamps emit monochromatic light generally in wavelengths of about 2537 angstroms or with the addition of suitable phosphors in the regions of 3000 and 3550 angstroms. Other utilizable light sources are ordinary fluorescent lamps which emit in the 3500-7000 angstrom region of the light spectrum. The lamps hereinbefore described are well known to those skilled in the art and are commercially available. Suitable lamps are described in greater detail in Ultraviolet Radiation by L. R. Coller, 2nd edition, John Wiley & Sons, Inc. (1965), which disclosure is incorporated herein by reference.

For optimum photobleaching effect, it is preferred to employ a source which has its greatest energy distribution concentrated within the range of about 2800 to about 7000 angstroms. It will be appreciated that electromagnetic radiation in this preferred range can be provided by employing lamps which emit principally in the desired region or by employing a combination of light source and filters. For example mercury arc lamps of the hereinbefore described types emitting a broad spectrum of light can be employed with suitable filters such as Pyrex to narrow the wavelength to about 2800 to 7000 angstroms.

The photochemical reaction of the present invention can be carried out over a wide range of temperatures. For example, the reaction can be conducted at a temperature from about 40 C. to about C. Since hydrogen peroxide tends to decompose at temperatures above about 100 C., it is preferred to effect the photobleaching of the present invention below this temperature, i.e., in the range of about 40 C. to 100 C. Especially preferred is the range of about 20 C. to about 65 C., for reasons of efliciency and optimal results. Because many of the lamps employed in the present invention, e.g., high pressure mercury lamps evolve heat, a cooling means is preferably employed to maintain the temperature of the photobleaching process within the prescribed temperature limits. Any suitable reaction pressure can be employed, the pressure generally ranging from about atmospheric to about 1000 p.s.i.g. depending on the photobleaching temperature, the nature of the solvent employed and the like.

The photochemical process can be conducted either batchwise or continuously, batchwise photobleaching being preferred. The constituents which comprise the solution irradiated as hereinbefore described can be introduced into a suitable irradiated zone or the constituents can be premixed and introduced into the irradiated zone as a mixture or mixtures.

It is preferred that the photochemical reaction of the present invention be conducted with agitation of the reactants. This can easily be accomplished by bubbling an inert gas such as nitrogen through the reaction medium during the irradiation. In addition, this inert atmosphere prevents quenching and contamination and possible competing side reactions. Other suitable means of agitating the material to be photobleached include the use of a falling [film technique or conventional stirring.

The photochemical irradiation of the present invention is conducted for a time suflicient to effect photobleaching which for purposes of the present invention refers to the attainment of improved color characteristics as well as to bleaching to substantial whiteness. While sulfonated a-olefin reaction products are generally photobleached to an improved color in about 1 minute to about 100 hours, and preferably in about minutes to 3 hours, the amount of time required to effect an improvement depends at least in part on the initial color of the sample prior to irradiation, the concentration of the sulfonated product in the solvent or vehicle, the temperature of reaction, the size of the sample which is irradiated, the physical proximity of the light source to the irradiated sample and the intensity of the light source employed.

The photobleaching of sulfonated a-olefins according to the present invention can be determined readily by conventional techniques, e.g., by observing the extent of decolorization as the reaction proceeds. -It is highly preferable to stop the reaction when the maximum decolorization has been obtained as determined visually. Further irradiation subsequent to this time may result in the formation of undesirable secondary products and is generally uneconomical from a time and efficiency standpoint.

The decolorized or photobleached product irradiated as described hereinbefore is removed from solution by conventional separation techniques as for example, by evaporation, filtration, or precipitation. A preferred technique is that of spray-drying which can be conducted by methods known in the detergent arts.

The sulfonated a-olefin reaction products which can be photobleached by the method of the present invention include any of the sulfonated a-olefin products known to those skilled in the art. The terms sulfonated a-olefin reaction product and er-olefin sulfonate are employed herein interchangeably to refer to any of the complex mixtures of reaction products of an a-olefin of about 10 to about 26 carbon atoms and a sulfonating agent such as oleum, chlorosulfonic acid, or sulfur trioxide. The photobleaching method of the present invention can be employed to advantage in the decolorization of the raw acid mix which results from the sulfonation reaction or of the neutralized forms which are prepared by conven tional neutralization procedures employing a basic reagent such as sodium hydroxide. The acid and neutralized forms are intended as being included in the hereinbefore specified recitations.

The photobleaching method of this invention is particularly useful in the decolorization of sulfonated a-olefin reaction products Which are derived from sulfonation of a-olefins of from about 10 to about 26 carbon atoms with gaseous sulfur trioxide. These reaction products are characterized by especially undesirable color properties particularly when process conditions for their manufacture are not carefully and/or optimally controlled. While applicants do not wish to be bound by any precise theory as to the cause of the undesirable discoloration, it is believed that it is at least in part due to the presence of localized concentrations of sulfur trioxide. These sulfonated a-olefin reaction products are generally prepared by sulfonating the a-olefin with gaseous sulfur trioxide according to any of the known batch or continuous sulfonating processes including, for example, vacuum sulfonation, air-dilution sulfonation or film reactor sulfonation systems.

The u-olefins which are employed in the preparation of these sulfonation products have from about 10 to about 26 carbon atoms, and preferably from 12 to 20 carbon atoms. These u-olefins can be derived from any convenient process, for example, wax cracking, ethylene buildup, and by dehydrating the primary alcohols obtained by hydrogenating fatty acids or their esters, those obtained from palm oil, tallow, coconut oil, and olive oil.

Examples of sulfonatable a-olefins include l-decene, l-undecene, l-dodecene, l-tridecene, l-tetradecene, l-pentadecene, l-hexadecene, l-heptadecene, l-octadecene, 1- nonadecene, l-eicosene, l-heneicosene, l-docosene, l-tricosene, l-tetracosene, l-pentacosene, and l-hexacosene. Mixtures of these compounds can also be used.

The sulfur trioxide sulfonating agent, generally used as a gas reactant, is used alone or with a diluent such as any of the commonly used inert gases, e.g., nitrogen, air, helium, argon, sulfur dioxide or the like. The sulfur trioxide can be derived from any convenient source, for example, from the burning of sulfur, from conventional oleum stripping or by heating liquid sulfur trioxide. The proportions of the sulfur trioxide sulfonating agent to the u-olefin raw material employed in carrying out sulfonation reactions range from less than stoichiometric amounts to an excess of the sulfonating agent, an excess being preferred. The temperature at which the sulfonation reaction takes places depends largely on the nature of the reactants and the different processing systems which can be employed. The sulfonating temperature ranges from about 0 C. to about C. and should preferably be within the range of about 25 C. to about 40 C.

The complex mixture of products resulting from the sulfonation reactions hereinbefore described is referred to in the art as an acid mix and is believed to consist essentially of a complex admixture of alkene-l-sulfonic acids; sultone inner esters having not less than five atoms in the cyclic group and highly polar polyfunctional disulfonated compounds. This acid mix can be photobleached by the method of the present invention prior to reaction with alkaline reagent and conversion to useful detergent compounds. Inert gases and unreacted sulfur trioxide can be removed from the sulfonation product prior to photobleaching.

The hydrolyzed and/or saponified sulfonated u-olefin reaction products which can be photobleached by the process of the present invention are the reaction products of an acid mix, hereinbefore described and approximately stoichiometric amounts of an alkaline reagent which can be inorganic or organic. Suitable inorganic alkaline materials include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, potassium bicarbonate, potassium carbonate, sodium oxide and the like. Suitable organic reagents include amines such as triethanolamine and substituted ammonium hydroxides.

The reaction of sulfonated a-olefin and alkaline reagent is conducted at a temperature of about 25 C. to about 250 C. for a time sufficient to neutralize, and thereby convert to salt compounds, the proton-bearing compounds of the acid mix and to cleave the sultone compounds of the acid mix to the corresponding hydroxyalkyl-l-sulfonates and alkenesulfonates. The proton bearing species of the acid mix are neutralized rapidly when brought in contact with the alkali material. Cleavage of sultone species normally occurs at a temperature in the range of about 100 C. to about 250 C. and preferably between about 120 C. and 170 C. The reaction product obtained upon completion of the neutralization and sultone-cleaving reactions is obtained in the form of a slurry or paste which can be photobleached as in the case of an acid mix in the manner hereinbefore described.

Examples of sulfonated ot-olefin reaction products which can be photobleached by the process of this invention include the sulfonated reaction products described in US. Pat. 2,061,618 (Nov. 24, 1936); U.S. Pat. 2,865,958 (Dec. 23, 1958); US. Pat. 2,940,936 (June 14, 1960); U.S. Pats. 3,332,874 through 3,332,880 (July 25, 1967); German Pat. 1,185,178 (Jan. 14, 1965); and Canadian Pat. 775,142 (Jan. 2, 1968). These references are incorporated herein by reference.

A preferred sulfonated ot-olefin reaction product which can be photobleached by the method of the present invention and which has excellent detergency properties is described in detail in commonly assigned and copending US. patent application, Ser. No. 561,352, filed June 29, 1966, by Kessler et al., now Pat. No. 3,488,384. This application is incorporated herein by reference. This sulfonated (It-Olefin reaction product is prepared by reaction of a sulfonated acid mix at from about C. to about 100 C. within about 2 seconds to about 15 minutes after completion of the sulfonation reaction with from about 1.0 to about 1.3 moles equivalent of alkali per mole of reacted sulfur trioxide followed by saponification. The saponification step comprises heating to a temperature I within a range of from about 100 C. to about 200 C.

This sulfonated a-Olefin reaction product when photobleached by the process of this invention is rendered substantially white in appearance and is adapted to employment in white detergent formulations.

Other highly preferred sulfonation products for photobleaching herein are those prepared by the film sulfonation processes described in commonly assigned and copending patent applications Ser. No. 514,468, filed Dec. 17, 1965, now Pat. No. 3,535,339, by Beyer et al.; and Ser. No. 565,262, filed July 14, 1966, now Pat. No. 3,531,518, by Ohren et al. These applications are incorporated herein by reference.

The photobleaching process of this invention provides a means of decolorizing sulfonated UL-Olefin. reaction products more efficiently in terms of time than either electromagnetic irradiation alone or hydrogen peroxide treatment alone. Moreover, the combined peroxide and irradiative treatment provides an effective and convenient means of decolorizing, in an aqueous or other vehicle, sulfonated u-olefin reaction products which as a class are not readily decolorized by conventional means.

EXAMPLES The following examples illustrate specific preferred embodiments of the present invention and are intended as being illustrative rather than limitative. All percentages and ratios in the following examples as well as in this specification and in the appended claims are by weight unless otherwise indicated. Hydrogen peroxide in each example was added as a 30 wt. percent aqueous solution. Temperatures are expressed in degrees centigrade.

In the following examples the extent of decolorization, where graded, was graded on the basis of the following color scale, which for convenience may be denoted as the Berry Color Scale. In this color grading system the grade 1 is ascribed to the color which corresponds to an equivolume mixture of a 5% aqueous solution of cobaltous chloride hexahydrate and an 0.5% aqueous solution of potassium dichromate. Higher grades, X, represent an X to 1 dilution of the l-grade solution with distilled water. Thus, a 200-grade is ascribed to a solution which is a 200:1 dilution of the l-grade solution. Similarly, a grade of 500 represents a 500:1 dilution of the l-grade solution. The l-grade solution, i.e., the equivolume mixture of cobaltous chloride hexahydrate and potassium dichromate solutions is dark amber .in color resembling strong tea. Solutions having color grades of 30 to 40 are light yellow and correspond in color to that of light straw while those having a 200-grade are faint yellow and are barely distinguishable from clear water. A 500-grade solution is virtually colorless and indistinguishable from clear water. Sulfonated Ot-OlCfiI'l detergent compounds having commercially acceptable color characteristics for use in detergent formulations have color grades of at least to in 35% aqueous solution and preferably about 200 which herein is defined as near-white or substantially white.

tln Examples I to VIII, the sulfonate ot-olefin reaction products which were subjected to photobleaching were prepared by the film sulfonation process described in detail in copending patent application Ser. No. 565,262, filed July 14, 1966, by Ohren et al., incorporated herein by reference. The sulfonated ot-olefin reaction product of Examples I to III, V and VI was prepared by neutralization and saponification of a C a-0l6fin/SO reaction product with sodium hydroxide. The product photobleached in Examples IV and VII was prepared by neutralization and saponification of a C a-olefin/SO reaction product with anhydrous ammonia. The product of Example VIII was prepared by neutralization and saponification with aqueous ammonia of the sulfonation product of sulfur trioxide and a 50:50 mixture of C and C u-olefin.

Example I A 35% solution of sodium olefin sulfonate of color grade 30 was photobleached by the following method:

An amount (75 ml.) of this aqueous solution was placed in a. 450-ml. Pyrex photochemical reaction vessel equipped with a nitrogen flush and a water-jacketed Vycor immersion well containing a Pyrex filter. Nitrogen was bubbled through the solution to provide agitation and 0.5 ml. of 30 weight percent solution of hydrogen peroxide added (0.57% hydrogen peroxide by weight of the olefin sulfonate). A 450-watt high-pressure mercury lamp having a total radiating energy of 175.8 watts was placed in the immersion well and the solution was irradiated for a 3-hour period. The high-pressure mercury lamp employed in this example was a Hanovia 679A-36 lamp characterized by the following spectral characteristics in watts:

Far U.V., 2200 A.-2800 A. 27.0 Middle U.V., 2800 A.3200 A 28.7 Near U.V., 3200 A.-4000 A 28.0 Visible, 4000 A.-6000 A. 75.7 Infra-red, 10,000 A.14,000 A 16.4

Total radiated energy 175.8

The irradiated sample was observed to undergo decolorization and attained a color grade of 75 after 2 hours irradiation and a color grade of 100 in 3 hours. A duplicate sample, Control, was placed in the dark at room temperature (25 C.) employing the same concentration of hydrogen peroxide. No photochemical treatment was employed. The Control sample did not undergo decolorization, i.e., the color grade was 30, after 3 hours in the dark.

Example II The procedure of Example I was repeated except that 1.1% hydrogen peroxide was added to the solution to be photobleached. The sample was photobleached for a period of 4 hours and was bleached to an essentially colorless solution. The following data summarizes the color grades visually noted upon the passage of the stated times.

9 Time, hours: Color grade 30 A control sample placed to react in the dark underwent no discernible color change in the same amount of time.

Example III The procedure of Example I was repeated except that 4.3% hydrogen peroxide was employed. The sample was irradiated for a period of 2 hours. The following data summarize the color grades attained with the passage of the stated times:

Time, hours: Color grade 0 30 A control sample underwent no discernible color change in the same amount of time.

Example IV The procedure of Example I was repeated except that the sample was an ammonium olefin sulfonate and hydrogen peroxide by weight of olefin sulfonate was employed. Prior to treatment the color grade of the sample was 10. Irradiation for a period of one hour resulted in photobleaching to a color grade of 50. A control sample allowed to react in the dark produced no discernible color improvement, the color grade remaining at 10.

Example V To ml. of a solution of the sodium alkenesulfonate product of Example I in a 50-ml. Pyrex Erlenmeyer flask was added 1% hydrogen peroxide by weight of the olefin suli'onate. The flask was allowed to stand in the path of direct sunlight for a period of 4 hours. The sample underwent photobleaching throughout the 4 hour irradiation period. The following table summarizes the color grades visually noted upon the passage of the stated times.

Time, hours: Color grade 0 30 A control solution allowed to react in the dark was not discernibly improved in color (color grade 30) in the same amount of time.

Example VI Example VII To 20 ml. of a 35% ammonium olefin sulfonate solution (color grade 15) was added 4.6% hydrogen peroxide by weight of the olefin sulfonate. The sample was irradiated for one hour with direct sunlight in the manner described in Example V and was photobleached to a color grade of 25. Continued irradiation improves the color characteristics. A control sample allowed to react for one hour in the dark was unchanged in color.

Example VIII A 30-ml. sample of 35% ammonium olefin sulfonate to which was added 5.8% hydrogen peroxide by weight of the ammonium olefin sulfonate was photobleached by the following method. The solution was placed into a 50 ml. Pyrex Erlenmeyer flask at room temperature, 25 C., and irradiated over a period of 24 hours. The photochemical process was conducted by placing the flask into the center of a circular array of sixteen 3500 angstrom ultraviolet lamps and exposing the sample to the radiation for a 24 hour period. The circular array of lamps is commercially available (distributed by the Southern New England Ultraviolet Company, Middletown, Conn.) as an array of lamps in a circle of 10" diameter as the Rayonet photochemical reactor. Two control samples were treated for purposes of comparison with the sample of the present example. One control sample was irradiated in the same manner as that of the present example except no hydrogen peroxide was employed, i.e., irradiation alone was employed. Another control sample was allowed to react with hydrogen peroxide in total darkness. The results are presented in the following table which summarizes the color grades visually noted upon the passage of the stated times.

Substantially similar results were obtained when the 3500 angstrom lamps were replaced by sixteen daylight fluorescent lamps having 4750 and 5750 angstrom maxima.

Example IX An olefin sulfonate acid mix (prepared by batch sulfonation at 40 C./l0 mm. Hg of l-hexadecene with 1.1 moles of uncomplexed gaseous sulfur trioxide for 30 minutes) having a color grade of 20 is photobleached in the following manner.

A 20% solution of the acid mix in water is prepared and admixed with 6% hydrogen peroxide by weight of the acid mix. A -ml. sample is photobleached employing the procedure and apparatus of Example I except that a medium-pressure mercury B-lOOA Blak-Ray lamp emitting principally in the 3660 angstrom region is employed. Irradiation for a period of about 4 hours renders the sample substantially white. Neutralization and saponification with sodium hydroxide in the manner hereinbefore described results in the formation of an excellent detergent product having desirable color characteristics.

Similar results are obtained when the following solvents are employed in the previous examples in lieu of water in that photobleachingof the sulfonated a-olefin reaction poducts occurs: methanol, ethanol, n-propyl alcohol, isopropyl alcohol, t-butyl alcohol, 2-ethyl hexyl alcohol, ndecyl alcohol, ethylene glycol, 1,3-propanediol, 1,6-dihydroxyhexane, 1,10-dihydroxydecane, dimethyl ether, diethyl ether, di-n-butyl ether, dioctyl ether, diphenyl ether, methyl phenyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane and diethylene glycol dimethyl ether.

Having thus described the invention, what is claimed is:

1. A process of improving the color characteristics of sulfonated alpha-olefin reaction products which comprises irradiating a solution of a sulfonated alpha-olefin reaction product and a solvent having low absorptivity for irradiation with electromagnetic radiation in the range of about 2000 to about 7000 angstroms and having an intensity of from about 1 10 to about l 1O einsteins/sec./

1 l cmfi; the irradiation being conducted in the presence of hydrogen peroxide.

2. The process of claim 1 wherein the sulfonated aolefin reaction product is present in an amount of from about 0.01% to about 50% of the solution.

3. The process of claim 2 wherein the hydrogen peroxide is present in an amount of about 0.3% to about 10% of the sulfonated a-olefin reaction poduct.

4. The process of claim 3 wherein the solvent is selected from the group consisting of water, alkanols, alkyl ethers, aromatic ethers, cyclic ethers and glycol ethers.

5. The process of claim 4 wherein the solution is irradiated with a high-pressure mercury arc lamp having a total power capacity ranging from about 50 watts to about 10,000 watts.

6. The process of claim 4 wherein the solution is irradiated with a low-pressure mercury lamp having a total 12 power capacity of from about 0.5 watt to about 50 watts.

7. The process of claim 4 wherein the sulfonated aolefin reaction product is an acid mix derived from sulfonation of an a-olefin having from about 10 to about 26 carbon atoms and sulfur trioxide.

8. The process of claim 4 wherein the sulfonated ocolefin reaction product is an alkali metal salt of an acid mix derived from sulfonation of an a-olefin having from about 10 to about 26 carbon atoms with sulfur trioxide.

9. The process of claim 8 wherein the sulfonation is conducted by film sulfonation.

References Cited FOREIGN PATENTS 983,056 2/1965 Great Britain 20458 HOWARD S. WILLIAMS, Primary Examiner 

